• 자원리싸이클링
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• 제2권2호
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• pp.16-21
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• 1993

본 연구에서는 폐수중에 함유된 철이온을 제거하기 위하여 2가와 3가 칠이온을 함유하는 용액의 pH를 침전점이상으로 조절함으로서 형성된 수산화철 침전의 침강 특성을 조가하여 다음과 같은 결과를 얻었다. 수산 이온의 농도 증가는 수산화철 침전의 침강 속도를 빠르게 하고 이때 CaO가 효과적이었다. 고분자 엉김제는 수산화철 침전의 초기 침강 속도를 빨라지게 하지만 과량은 침강 속도를 저하시킨다. 수산화철 침전의 농도가 높아지면 침강 속도가 크게 감소되므로 수산화물로서 침전시켜 제거할 철이온의 농도는 $10^{-2}$mol/ㅣ이하로 조절됨이 바람직하다.

• Advances in aircraft and spacecraft science
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• 제2권3호
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• pp.275-302
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• 2015

Theoretical and numerical assessments of approximate evaluations and simplified analyses of piezoelectric structures transverse shear modal effective electromechanical coupling coefficient (EMCC) are presented. Therefore, the latter is first introduced theoretically and its approximate evaluations are reviewed; then, three-dimensional (3D) and simplified two-dimensional (2D) plane-strain (PStrain) and plane-stress (PStress) piezoelectric constitutive behaviors of electroded shear piezoceramic patches are derived and corresponding expected short-circuit (SC) and open-circuit (OC) frequencies and resulting EMCC are discussed; next, using a piezoceramic shear sandwich beam cantilever typical benchmark, a 3D finite element (FE) assessment of different evaluation techniques of the shear modal effective EMCC is conducted, including the equipotential (EP) constraints effect; finally, 2D PStrain and PStress FE modal analyses under SC and OC electric conditions, are conducted and corresponding results (SC/OC frequencies and resulting effective EMCC) are compared to 3D ones. It is found that: (i) physical EP constraints reduce drastically the shear modal effective EMCC; (ii) PStress and PStrain results depend strongly on the filling foam stiffness, rendering inadequate the use of popular equivalent single layer models for the transverse shear-mode sandwich configuration; (iii) in contrary to results of piezoelectric shunted damping and energy harvesting popular single-degree-of-freedom-based models, transverse shear modal effective EMCC values are very small in particular for the first mode which is the common target of these applications.

• Geomechanics and Engineering
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• 제23권6호
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• pp.561-573
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• 2020

The creep and consolidation behaviors of clays subjected to thermal cycles are of fundamental importance in the application of energy geostructures. This study aims to numerically investigate the physical mechanisms for the temperature-triggered volume change of saturated clays. A recently developed thermodynamic framework is used to derive the thermo-mechanical constitutive model for clays. Based on the model, a fully coupled thermo-hydro-mechanical (THM) finite element (FE) code is developed. Comparison with experimental observations shows that the proposed FE code can well reproduce the irreversible thermal contraction of normally consolidated and lightly overconsolidated clays, as well as the thermal expansion of heavily overconsolidated clays under drained heating. Simulations reveal that excess pore pressure may accumulate in clay samples under triaxial drained conditions due to low permeability and high heating rate, resulting in thermally induced primary consolidation. Results show that four major mechanisms contribute to the thermal volume change of clays: (i) the principle of thermal expansion, (ii) the decrease of effective stress due to the accumulation of excess pore pressure, (iii) the thermal creep, and (iv) the thermally induced primary consolidation. The former two mechanisms mainly contribute to the thermal expansion of heavily overconsolidated clays, whereas the latter two contribute to the noticeable thermal contraction of normally consolidated and lightly overconsolidated clays. Consideration of the four physical mechanisms is important for the settlement prediction of energy geostructures, especially in soft soils.

• 한국광물학회지
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• 제18권4호통권46호
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• pp.313-323
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• 2005

탄자리아산 강옥의 보석광물학적 특성을 파악하기 위하여 XRD, XRF, EPMA, FT-IR과 SEM-CL 분석을 수행하였다. 탄자니아산 강옥은 장파장 자외선이나 단파장 자외선에서 거의 형광반응이 나타나지 않는다. 탄자니아산 강옥은 내포물의 종류에 따라 5가지 유형으로 분류될 수 있으며, 유형 I은 액상 내포물 풍부한 형태, 유형 II는 기상 내포물 풍부한 형태, 유형 III은 액상 $CO_{2}$를 함유한 형태, 유형 IV는 고상 내포물을 함유한 형태, 유형 V는 유체 포유물과 고상 내포물 및 딸광물(daughter mineral)이 공생하는 복합 내포물 형태이다. 탄자니아산 강옥의 SEM-CL분석에서 성장구조가 수반된 쌍정조직, 스피넬 반정, 괴상조직과 누대조직 등이 관찰된다. 루비와 사파이어는 크롬과 철의 함량에 의해 뚜렷이 구분되며, $Al_{2}O_{3}/100-Cr_{2}O_{3}-Fe_{2}O_{3}$ 다이어그램에서 각각 고유한 영역에 도시된다. FT-IR 분석결과, 탄자니아산 강옥 시료들이 모두 유사한 양상을 보이고 있으며, $455.09\~459.23\;cm^{-1},\;603.15\~611.71\;cm^{-1},\;1509.00\~1655.05\;cm^{-1}$와 $3436.41\~3468.87\;cm^{-1}$에서 흡수 피크가 관찰된다. 연구 결과는 탄자니아산 강옥의 감별 및 산지 추측에 유용한 정보로 활용될 수 있다.

• 대한지역사회영양학회지
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• 제14권3호
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• pp.327-339
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• 2009

It is known that Korean pregnant women take iron supplements at a higher than the recommended level. This study was designed to provide data on current iron intake levels both from food sources and supplement to better guide iron supplement use during pregnancy. We also explored associations of iron supplement intake levels with various sociocultural factors and pregnancy outcomes. Dietary intakes of 510 pregnant women were assessed by a validated 102-item food frequency questionnaire, and information on types and amounts of nutritional supplement intakes were also attained. While dietary intake levels of most nutrients exceeded the KDRIs (Korea Dietary Reference Intakes: EAR: Estimated Average Requirements), folate fell short of the KDRIs. A total of 428 women (83.9%) reported to take iron supplement. The pregnant women were divided into the three groups (group I: Fe supplement intake ${\le}$ EAR, group II: EAR < Fe supplement intake ${\le}$ 3 times of EAR, group III: 3 times of EAR < Fe supplement intake). The mean dietary intake of iron was 24% of the total iron intake for pregnant women. Iron intake from food was not significantly different among I, II, and III. In case of iron intake from supplements, the most frequent dose (34.1%) was 90-100 mg/day, and the mean iron supplement intake was 362% of the EAR. The study findings showed that those with higher levels of iron supplements had better meal quality measured by NAR (Nutrient Adequacy Ratio) and INQ (Index of Nutrient Quality). In addition iron supplement intake levels were significantly related to age (20s: 66.5 ${\pm}$ 38.6 mg/day, 30s: 77.3 ${\pm}$ 47.8 mg/day, p < 0.0116) and experience of childbirth (1st pregnancy: 70.9 ${\pm}$ 41.2 mg/day, 2nd pregnancy: 64.5 ${\pm}$ 39.5 mg/day, ${\ge}$ 3rd pregnancy: 94.4 ${\pm}$ 63.8 mg/day, p < 0.005). However, no significant difference was found between iron supplement intake levels and various pregnancy outcomes including birth weight, birth height, gestational age, weight gain during pregnancy, and jaundice. It is worrisome that iron intake by supplement use greatly exceeded the EAR, suggesting the need of appropriate guidelines for iron supplement intake during pregnancy. Thus iron overdose from supplements in pregnancy should be considered as a serious condition.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.800-811
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• 2014

Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses in details these three aspects of wind noise simulation and recommends appropriate methods to deliver required results at the right time based on i) simulation and experimental data availability, ii) design stage at which a decision must be made and iii) time available to deliver these results. Several simulation methods are used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. Furthermore, a 1D and 2D wavenumber transformation is used to extract key parameters such as the convective and the acoustic component of the turbulent flow from CFD and/or experimental data whenever available. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.540-546
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• 2004

We deviced a new graphite-Mn(II) electrode and found that the modified electrode with Mn(II) can catalyze NADH oxidation and $NAD^+$ reduction coupled to electricity production and consumption as oxidizing agent and reducing power, respectively. In fuel cell with graphite-Mn(II) anode and graphite-Fe(III) cathode, the electricity of 1.5 coulomb (A x s) was produced from NADH which was electrochemically reduced by the graphite-Mn(II) electrode. When the initial concentrations of pyruvate and acetaldehyde were adjusted to 40 mM and 200 mM, respectively, about 25 mM lactate and 35 mM ethanol were produced from 40 mM pyruvate and 200 mM acetaldehyde, respectively, by catalysis of ADH and LDH in the electrochemical reactor with $NAD^+$ as cofactor and electricity as reducing power. By using this new electrode with catalytic function, the bioelectrocatalysts are engineered; namely, oxidoreductase (e.g., lactate dehydrogenase) and $NAD^+$ can function for biotransformation without electron mediator and second oxidoreductase for $NAD^+$/NADH recycling.

• 동아시아식생활학회지
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• 제13권1호
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• pp.56-63
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• 2003

증류수, 수도수, 온천수 희석액(55배 희석, 4배 희석, 2배희석)을 사용한 반죽의 발효특성과 빵의 품질에 미치는 영향을 조사하였다. 사용한 온천수의 총고형물 함량은 8,765 ppm 이였으며 주요 무기질로는 Na가 2296 ppm, Ca가 287 ppm, Mg와 K가 각각 65 및 8 ppm을 함유하였다. Fe, Cu, Co, F. Zn, Al, S, Mo, Se 및 Si 등이 0.002~5.2 ppm을 함유하였다. 온천수를 사용한 반죽의 pH는 6.95~7.68로 증류수의 6.40보다 높았다. 반죽부피는 온천수의 농도가 높아짐에 따라 감소하였다. pH를 5.5로 조정한 온천수를 사용한 반죽의 부피는 대조구 보다 오히려 높았다. 온천수를 사용한 빵의 경도와 신장성은 대조구보다 높았으나 pH를 조정한 온천수기 경우는 낮았다. 점착성은 경도 및 신장성과는 역으로 희석 온천수에서 낮았다. pH조정 또는 조정 없이 구운 빵의 부드러운 정도는 2배로 희석한 온천수가 증류수 및 55배, 2배 희석 온천수보다 높았다. 쫄깃한 정도는 전반적으로 온천수가 대조구에 비하여 높았으며 종합적인 맛은 4배로 희석한 온천수가 가장 좋았다.

• 한국식품영양과학회지
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• 제19권6호
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• pp.625-635
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• 1990

발아중인 옥수수에서의 전분의 가수분해효소인 amylases의 종류를 규명하고자 황산 암모늄염석법, DEAE-Sephadex A-50을 이 용한 이온교환칼럼법과 Sephadex G-100 Gel filtration chromatography 방법으로 정제하였으며 전분가수분해 효소는 3개의 peak가 나타났으며, 이를 각각 모아서 정제한 결과 각각의 비활성은 70.47(units/mg), 62.98(units/mg), 80.39(units/mg)으로 저단백식품의 하나인 옥수수임에도 불구하고 높은 활성을 나타내었다. 이것은 발아중 가수분해되는 전분체내에 이 효소의 작용이 커졌음을 유리당의 양이 증가하였음으로 알 수 있었다. 또한 고속액체 크로마토그라피를 이용하여 분석한 결과 3종류의 amylases중에 amylases(I)은 $\alpha$-amytotetrose의 종류로 밝혀졌으며, amylase(II)와 (III)는 각각, 주로 maltotetrose의 단위로 가수분해하는 전분 분해 효소이나. 서로 생물학적 성격에서 약간씩의 차이를 보이므로 같은 종류는 아닐 것으로 사료되었다.

• 대한기계학회논문집A
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• 제28권5호
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• pp.524-531
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• 2004

To investigate relevance of the definition of the reference stress to estimate J and $C^{*}$ for surface crack problems, this paper compares FE J and $C^{*}$ results for surface cracked pipes with those estimated according to the reference stress approach using various definitions of the reference stress. Pipes with part circumferential inner surface crack and finite internal axial crack are considered, subject to internal pressure and global bending. The crack depth and aspect ratio are systematically varied. The reference stress is defined in four different ways using (i) the local limit load, (ii) the global limit load, (iii) the global limit load determined from the FE limit analysis, and (iv) the optimized reference load. It is found that the reference stress based on the local limit load gives overall excessively conservative estimates of J and $^{*}$. Use of the global limit load clearly reduces the conservatism, compared to that of the local limit load, although it can provide sometimes non-conservative estimates of J and $^{*}$. The use of the FE global limit load gives overall non-conservative estimates of J and $^{*}$. The reference stress based on the optimised reference load gives overall accurate estimates of J and $^{*}$, compared to other definitions of the reference stress. Based on the present finding, general guidance on the choice of the reference stress for surface crack problems is given.